Optimization of the sex pheromone of the rice leaffolder moth Cnaphalocrocis medinalis as a monitoring tool in China.

The crude extract from Cnaphalocrocis medinalis ( Lepidoptera, Pyralidae) has been identified to be (Z)-11-octadecenal (Z11-18:Ald), (Z)-13-octadecenal (Z13-18:Ald), (Z)-11-octadecen-1-ol (Z11-18:OH) and (Z)-13-octadecen-1-ol (Z13-18:OH) in the GC-MS, confirming the results reported previously in Japan. Field evaluation in China showed that the optimal blend is Z11-18:Ald, Z13-18:Ald, Z11-18:OH and Z13-18:OH at a ratio of 3 : 25 : 3 : 3. The optimal dosage is 500 μg Z13-18:Ald per PVC tubing lure. In August, trap catches were highest between 3:00 and 4:00 a.m., and no moths were caught before 12:00 a.m. or after 6:00 a.m. The impact of trap design and trap height placement was also evaluated in the paddy field. The sticky wing trap was better than the water pan trap. The number of moths captured by the electric grid trap was 1.7 times greater than caught by the sticky wing trap. The optimal trap height was 20 cm below the top of the rice plants (80 cm high). Pheromone lure formulated from 60 μg Z11-18:Ald, 500 μg Z13-18:Ald, 60 μg Z11-18:OH and 60 μg Z13-18:OH was effective for population monitoring in trial sites in Zhejiang, Shanghai, Jiangxi, Hunan, Hubei, Guangxi, Guizhou, Chongqing and Hainan Provinces, encompassing both subtropical and temperate regions. Use of this synthetic pheromone blend provides a promising alternative to the currently used disturb and count method ( DCM) for monitoring the population of C. medinalis in China. [ABSTRACT FROM AUTHOR]